Replacing engineered trusses with rafters

I am intersted in remodeling an attic above my detached garage that was built with fink type engineered trusses. Assuming the load bearing walls below are to code, is there someway to open space by converting to rafters without removing the entire roof and starting over. Could I somehow reinforce floor joists (22'span) and butt 6" rafters next to roof portion of trusses and cut way the interior web taking up the space.